Bleeding under a nail, called a subungual hematoma, happens when blood pools between the nail plate and the nail bed after a crush injury, slam, or heavy impact. The blood has nowhere to go, so pressure builds in that tight space and causes intense throbbing pain. The good news: most cases can be managed at home with simple first aid, and the nail will eventually grow out and replace itself. Here’s what to do right now and what to watch for.
Immediate Steps to Take
Start with the basics: rest, ice, compression, and elevation. Apply an ice pack wrapped in a thin cloth (never directly on skin) to the injured finger or toe for 10 to 20 minutes at a time, repeating every hour or two as needed. Ice helps slow the bleeding beneath the nail and reduces swelling. Between icing sessions, keep the hand or foot elevated above the level of your heart. Propping your hand on a pillow while sitting or lying down is enough. Elevation uses gravity to limit how much blood continues pooling under the nail.
If the nail or surrounding skin is broken, gently rinse the area with clean water. Avoid hydrogen peroxide or rubbing alcohol, both of which can slow healing. Pat the area dry and cover it with a non-stick bandage to keep debris out.
For pain, over-the-counter anti-inflammatories like ibuprofen work well because they reduce both swelling and discomfort. If you can tolerate it, acetaminophen is another option purely for pain relief. Avoid aspirin if the nail is still actively bleeding, since aspirin thins the blood and can make the bleeding harder to control.
Why It Hurts So Much
Your nail sits on a dense, nerve-rich bed of tissue, and the nail plate above it is rigid. When blood collects in that space, even a small amount creates significant pressure with nowhere to expand. That trapped pressure is what produces the severe, pulsing pain that often feels out of proportion to the injury itself. The pain typically peaks within the first few hours and gradually eases as the bleeding stops and the pressure stabilizes.
When the Blood Needs to Be Drained
If the dark area under the nail covers a large portion of the nail surface, the pressure may be too great for ice and elevation alone to relieve. In these cases, a doctor can perform a procedure called trephination: creating a small hole through the nail plate to let the trapped blood escape. The relief is almost immediate because the pressure drops as soon as blood drains out.
Doctors typically use one of three tools: a heated paperclip tip, a hollow-tip needle, or an electrocautery pen. The instrument is held perpendicular to the nail and gently worked through the nail plate until it reaches the blood pocket underneath. Because the nail plate itself has no nerves, the procedure is less painful than it sounds. Most people feel pressure and then a rush of relief when the blood releases.
You may have seen tutorials online about doing this at home with a heated paperclip. While the basic concept is the same one doctors use, doing it yourself carries real risks: burning the nail bed, pushing too deep and damaging the tissue underneath, or introducing bacteria into what is essentially an open wound over bone. If you’re in enough pain that you’re considering self-drainage, that’s a sign the injury is significant enough to get checked out.
Caring for the Nail Afterward
Whether the blood was drained or left to resolve on its own, the aftercare is straightforward. Wash the injured nail gently with clean water twice a day and keep it clean and dry the rest of the time. Cover it with a non-stick bandage, especially if the nail is loose or if trephination was performed. A loose nail can catch on things and tear further, so keeping it bandaged and trimmed helps prevent that.
The dark discoloration under the nail won’t disappear overnight. As your nail grows, the bruised area slowly moves toward the tip and eventually gets trimmed away. Fingernails grow at roughly 3.5 millimeters per month, so a mid-nail hematoma might take three to six months to fully grow out. Toenails are slower, averaging about 1.6 millimeters per month, which means a bruised big toenail can take nine months to a year to look normal again. Younger people and men tend to have slightly faster growth rates, but the difference is modest.
Signs the Injury Is More Serious
A simple hematoma is one thing. But a hard enough impact to cause heavy bleeding under the nail can also fracture the bone underneath (the distal phalanx) or lacerate the nail bed itself. Watch for these warning signs:
- Deformity or unusual bend in the fingertip, which could signal a fracture
- Numbness or tingling beyond the immediate area of injury
- Bleeding that won’t stop even after 20 minutes of direct pressure and elevation
- A nail that’s partially or fully detached from the nail bed
- Increasing redness, warmth, or pus in the days following the injury, which suggests infection
If the fingertip looks crushed or the nail is badly split, an X-ray may be needed. Fractures beneath the nail bed sometimes require the nail to be removed so a doctor can repair the lacerated tissue underneath with fine sutures.
Dark Streak vs. Bruise: A Key Distinction
Most bleeding under a nail appears quickly, within hours of an injury, and looks like a dark bruise or smudge. It moves gradually toward the nail tip as the nail grows. But if you notice a dark line or streak under a nail that appeared without any injury, grows slowly, or doesn’t move with nail growth, that’s a different situation. Subungual melanoma, a rare form of skin cancer, can mimic a bruise under the nail. One distinguishing feature is the Hutchinson sign, where the dark discoloration extends beyond the nail onto the surrounding skin. A hematoma from an injury grows out with the nail and eventually disappears when you trim it. A melanoma streak persists and often widens over weeks to months. If you have a dark mark under a nail with no clear cause, getting it evaluated is worthwhile.